Balance Sheet Components - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 78,831	$ 106,046	$ 125,425
Restricted cash included in other assets	300		300
Total cash, cash equivalents and restricted cash shown in the condensed consolidated statement of cash flows	$ 79,131	$ 106,346	$ 125,725	$ 100,536